(1) Field of the Invention
The present invention relates to insuring the correct positioning of movable members such as valve actuators and particularly to a technique for determining, from a remote location, the position of each of a plurality of adjustable members. More specifically, this invention is directed to apparatus for providing an indication of positioning errors of movable members and especially to apparatus for determining the position of a valve member without breaching the valve housing. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
(2) Description of the Prior Art
While not limited thereto in its utility, the present invention is particularly well-suited for use in ascertaining the condition of remotely located fluid flow control devices. There has been a long-standing need in the art for apparatus having the capability of reliably determining and indicating, at a remote location, the position of movable valve members relative to the valve seats with which such valve members cooperate. In a power plant, especially a nuclear power plant, there are a large number of valves located at various sites throughout the facility over which the plant operator must exercise supervision and control. The proper positioning of the valve members of these valves is essential to proper plant operation. Some of these valves will usually be inconveniently located and/or located so as to be in a harsh, typically high temperature, operating environment.
In the operation of existing power plants employed in the generation of electricity many of the control valves are adjustable manually. Manual control presents two potential problems. Firstly, because of the large number of valves which must be controlled, there is an inherent possibility that the technician may become confused as to valve identity. Secondly, although the correct valve is selected for adjustment, human error leads to the possibility of incorrect adjustment.